One known pull-type clutch cover assembly includes a release bearing assembly which can be mounted or removed by engaging or disengaging the bearing body of the assembly with a diaphragm spring-holding ring. The bearing body acting as a friction clutch is mounted so as to be axially movable within a given range. The release bearing assembly can be divided into parts in this way to secure space which permits the transmission to be mounted and removed easily.
Japanese Patent Laid-Open No. 37522/1987 discloses an automotive friction clutch of this type. The release bearing assembly of this clutch is shown in FIG. 10, where the body of the bearing is coupled to a retainer ring. In this state, a hub or inner ring 7 is kept in engagement with the retainer ring 3 by the interposition of a split ring 4 which is an annular spring having a partially cutaway circular cross section. In order to disassemble the release bearing assembly, a split cylindrical sleeve 5 having an inclined and thinned front end portion is moved with the hub 7 in the direction indicated by the arrow B, or to the left as viewed in FIG. 11. The ring 4 is pushed and spread between the inclined portion of the sleeve 5 and the wall forming a groove 10 that is formed in the retainer ring 3. The ring 4 is so placed as to ride on the outer periphery of the sleeve 5. Under this condition, the hub 7 is moved in the direction indicated by the arrow A, or to the right as viewed in FIG. 11. The ring 4 can ride across a protrusion 26 formed at the front end of the hub, so that the hub 7 and the retainer ring 3 can be disassembled. When reassembly is performed, the split ring 4 is placed in the groove 10 formed in the retainer ring 3. The hub 7 is moved toward the retainer ring 3. Thus, the split ring 4 is spread by the inclined front end portion 11 of the hub 7 and permitted to ride across the protrusion 26. A stopper 6 is formed between the hub 7 and the retainer ring 3 to prevent them from moving toward each other. This, in turn, prevents the split ring 4 from coming off during operation.
The above-described release bearing of the friction clutch requires three parts for disassembly and assembly, i.e., the split ring 4, the split cylindrical sleeve 5, and the stopper 6. Since the numerous parts are needed, any one of them frequently fails to be mounted after disassembly. If the sleeve 5 fails to be mounted, the assembly cannot be disassembled after the assembly operation is completed. If the stopper 6 fails to be mounted, the assembly will be disassembled due to vibration during the operation. In this way, various problems occur. Also, the split ring 4 must be fabricated to a very close tolerance because of the relation between the inside diameter of the retainer ring 3 and the outside diameter of the hub 7. In addition, if the friction produced between the ring 4 and the sleeve 5 is not greater than the friction produced between the split cylindrical sleeve 5 and the hub 7, then the sleeve 5 disengages from the ring 4 at the final step of disassembly operation, i.e., when the hub 7 is moving in the direction indicated by the arrow A. Then, the diameter of the ring 4 decreases. As a result, the hub 7 and the ring 3 cannot be removed. Another problem is that the sleeve 5 is required to be moved to the right relative to the hub 7 during reassembly.